login · FakeStore MCP: Risk & Policy

Q: What risk level is login?

login is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

WHAT IT DOES

What login does on FakeStore MCP

AI agents use login to create or update resources in FakeStore MCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your FakeStore MCP environment.

WHY IT NEEDS A POLICY

Why login needs a policy

Login creates an authenticated session (a stateful side effect), which is a reversible write-like operation. It does not merely read data, and it doesn't delete or execute code. The sibling 'logout' tool further confirms session state is created/modified. Severity is medium because a compromised login could grant access to user account operations like cart management and order data.

From the tool's definition Authenticate user with FakeStore API

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

login stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "login": {
      "limits": [
        {
          "counter": "login_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches FakeStore MCP, so you can run agents against it safely.

FAQ

Questions about login

What does the login tool do? +

Authenticate user with FakeStore API. It is categorised as a Write tool in the FakeStore MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on login? +

Register the FakeStore MCP server in PolicyLayer and add a rule for login: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches FakeStore MCP. Nothing to install.

What risk level is login? +

Can I rate-limit login? +

Yes. Add a rate_limit block to the login rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block login completely? +

Set action: deny in the PolicyLayer policy for login. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides login? +

login is provided by the FakeStore MCP server (mithgroth/fakestore-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.